Nonlinear Free Vibration of Nanobeams With Surface Effects Considerations

2011 ◽  
Author(s):  
Ali Fallah ◽  
Keikhosrow Firoozbakhsh ◽  
Mohammad Hossein Kahrobaiyan ◽  
Abdolreza Pasharavesh
Keyword(s):  
Differential Equation ◽  
Boundary Conditions ◽  
Nonlinear Partial Differential Equation ◽  
Surface Elasticity ◽  
Beam Theory ◽  
Surface Effects ◽  
Nonlinear Ordinary Differential Equation ◽  
Euler Bernoulli Beam ◽  
Analytical Expressions ◽  
Equations Of Motions

In this paper, simple analytical expressions are presented for geometrically non-linear vibration analysis of thin nanobeams with both simply supported and clamped boundary conditions. Gurtin-Murdoch surface elasticity together with Euler-Bernoulli beam theory is used to obtain the governing equations of motions of the nanobeam with surface effects consideration. The governing nonlinear partial differential equation is reduced to a single nonlinear ordinary differential equation using Galerkin technique. He’s variational approach is employed to obtain analytical solution for the resulted nonlinear governing equation. The effects of different parameters such as vibration amplitude, boundary conditions, and beam dimensions on the natural frequencies of nanobeams are investigated and results are presented for future studies.

Asymmetric Bifurcation of Initially Curved Nanobeam

2015 ◽  
Vol 82 (9) ◽  
Author(s):  
X. Chen ◽  
S. A. Meguid
Keyword(s):  
Symmetry Breaking ◽  
Degrees Of Freedom ◽  
Surface Elasticity ◽  
Beam Theory ◽  
Surface Effects ◽  
Beam Model ◽  
Bernoulli Beam ◽  
Reduced Order ◽  
Euler Bernoulli Beam ◽  
Bifurcation Behavior

In this paper, we investigate the asymmetric bifurcation behavior of an initially curved nanobeam accounting for Lorentz and electrostatic forces. The beam model was developed in the framework of Euler–Bernoulli beam theory, and the surface effects at the nanoscale were taken into account in the model by including the surface elasticity and the residual surface tension. Based on the Galerkin decomposition method, the model was simplified as two degrees of freedom reduced order model, from which the symmetry breaking criterion was derived. The results of our work reveal the significant surface effects on the symmetry breaking criterion for the considered nanobeam.

Nonlinear Vibration Solutions of Nano-Beams Considering Surface Effects

2013 ◽  
Author(s):  
Hassan Askari ◽  
Ebrahim Esmailzadeh ◽  
Davood Younesian
Keyword(s):  
Differential Equation ◽  
Harmonic Balance ◽  
Nonlocal Parameter ◽  
Harmonic Balance Method ◽  
Beam Theory ◽  
Surface Effects ◽  
Nonlinear Ordinary Differential Equation ◽  
Balance Technique ◽  
Governing Differential Equation ◽  
Relationship Of

Nonlinear free vibration of nanobeams considering the surface effects is studied. The governing differential equation of motion of the system employing the Euler-Bernoulli beam theory is derived. Galerkin method is utilized to obtain the nonlinear ordinary differential equation of nanobeams, which is a well-known type of the Duffing equation. The elliptical harmonic balance method, energy balance technique and the variational approach are employed to obtain the frequency-amplitude relationship of the system. The effects of different parameters, i.e., aspect ratio, nonlocal parameter and the resultant residual stress, on the natural frequency are examined. Moreover, the variation of the amplitude on the frequency response is studied. The influence of the initial amplitude on the obtained modulus from the elliptical harmonic balance has been examined. Furthermore, the exact numerical solution is determined to verify the results obtained from the analytical solutions.

Nonlinear Vibration Analysis of Functionally Graded Nanobeam Using Homotopy Perturbation Method

2016 ◽  
Vol 9 (1) ◽  
pp. 144-156 ◽  
Author(s):  
Majid Ghadiri ◽  
Mohsen Safi
Keyword(s):  
Differential Equation ◽  
Perturbation Method ◽  
Homotopy Perturbation Method ◽  
Nonlinear Partial Differential Equation ◽  
Beam Theory ◽  
Nonlocal Elasticity Theory ◽  
Functionally Graded ◽  
Simply Supported ◽  
Homotopy Perturbation ◽  
Functionally Graded Nanobeam

AbstractIn this paper, He's homotopy perturbation method is utilized to obtain the analytical solution for the nonlinear natural frequency of functionally graded nanobeam. The functionally graded nanobeam is modeled using the Eringen's nonlocal elasticity theory based on Euler-Bernoulli beam theory with von Karman nonlinearity relation. The boundary conditions of problem are considered with both sides simply supported and simply supported-clamped. The Galerkin's method is utilized to decrease the nonlinear partial differential equation to a nonlinear second-order ordinary differential equation. Based on numerical results, homotopy perturbation method convergence is illustrated. According to obtained results, it is seen that the second term of the homotopy perturbation method gives extremely precise solution.

Investigation of the Oscillatory Behavior of Electrostatically-Actuated Microbeams

2010 ◽  
Author(s):  
Mahdi Mojahedi ◽  
Mahdi Moghimi Zand ◽  
Mohammad Taghi Ahmadian
Keyword(s):  
Differential Equation ◽  
Homotopy Perturbation Method ◽  
Axial Stress ◽  
Nonlinear Partial Differential Equation ◽  
Nonlinear Ordinary Differential Equation ◽  
Oscillatory Behavior ◽  
Electrostatically Actuated ◽  
Homotopy Analysis ◽  
Analytic Expressions ◽  
Good Agreement

Vibrations of electrostatically-actuated microbeams are investigated. Effects of electrostatic actuation, axial stress and midplane stretching are considered in the model. Galerkin’s decomposition method is utilized to convert the governing nonlinear partial differential equation to a nonlinear ordinary differential equation. Homotopy perturbation method (i.e. a special and simpler case of homotopy analysis method) is utilized to find analytic expressions for natural frequencies of predeformed microbeam. Effects of increasing the voltage, midplane stretching, axial force and higher modes contribution on natural frequency are also studied. The anayltical results are in good agreement with the numerical results in the literature.

Surface Effects on the Buckling of Piezoelectric Nanobeams

2012 ◽  
Vol 486 ◽  
pp. 519-523 ◽  
Author(s):  
Kai Fa Wang ◽  
Bao Lin Wang
Keyword(s):  
Shear Deformation ◽  
Electric Potential ◽  
Surface Stress ◽  
Surface Elasticity ◽  
Beam Theory ◽  
Surface Effects ◽  
Residual Surface Stress ◽  
Buckling Behavior ◽  
Stress Surface ◽  
Piezoelectric Nanobeam

In this paper, we analyze the influence of surface effects including residual surface stress, surface piezoelectric and surface elasticity on the buckling behavior of piezoelectric nanobeams by using the Timoshenko beam theory and surface piezoelectricity model. The critical electric potential for buckling of piezoelectric nanobeams with different boundary condition is obtained analytically. From the results, it is found that the surface piezoelectric reduces the critical electric potential. However, a positive residual surface stress increases the critical electric potential. In addition, the shear deformation reduces the critical electric potential, and the influence of shear deformation become more significant for a stubby piezoelectric nanobeam.

Dynamic Behavior of Sandwich Beams with Different Cores

2012 ◽  
Vol 468-471 ◽  
pp. 1344-1348
Author(s):  
Ying Wu ◽  
Han Bin Jia ◽  
Dong Xu Zhang ◽  
Lei Tian ◽  
Yan Jun Lü
Keyword(s):  
Dynamic Behaviour ◽  
Metal Foam ◽  
Lattice Structure ◽  
Beam Theory ◽  
Porous Metal ◽  
Nonlinear Ordinary Differential Equation ◽  
Sandwich Beams ◽  
Bernoulli Beam ◽  
Metal Fiber ◽  
Euler Bernoulli Beam

The nonlinear dynamic behaviour of sandwich beams with different cores under transverse cycling loads is investigated in this paper. Based on Euler-Bernoulli beam theory, the second-order nonlinear ordinary differential equation of the sandwich beams with different cores is established by applying Hamilton’s principle and Galerkin method. The effects of the cores of metal foam and lightweight wood and porous metal fiber as well as pyramid lattice structure on the dynamic behaviour are studied through numerical simulations. It is shown that the dynamic behaviour of sandwich beams is not solely determined by and

Exact solutions for the bending of Timoshenko beams using Eringen’s two-phase nonlocal model

2018 ◽  
Vol 24 (3) ◽  
pp. 559-572 ◽  
Author(s):  
Yuanbin Wang ◽  
Kai Huang ◽  
Xiaowu Zhu ◽  
Zhimei Lou
Keyword(s):  
Differential Equations ◽  
Boundary Conditions ◽  
Exact Solutions ◽  
Nonlocal Parameter ◽  
Beam Theory ◽  
Nonlocal Model ◽  
Bernoulli Beam ◽  
Two Phase ◽  
Differential Model ◽  
Euler Bernoulli Beam

Eringen’s nonlocal differential model has been widely used in the literature to predict the size effect in nanostructures. However, this model often gives rise to paradoxes, such as the cantilever beam under end-point loading. Recent studies of the nonlocal integral models based on Euler–Bernoulli beam theory overcome the aforementioned inconsistency. In this paper, we carry out an analytical study of the bending problem based on Eringen’s two-phase nonlocal model and Timoshenko beam theory, which accounts for a better representation of the bending behavior of short, stubby nanobeams where the nonlocal effect and transverse shear deformation are significant. The governing equations are established by the principal of virtual work, which turns out to be a system of integro-differential equations. With the help of a reduction method, the complicated system is reduced to a system of differential equations with mixed boundary conditions. After some detailed calculations, exact analytical solutions are obtained explicitly for four types of boundary conditions. Asymptotic analysis of the exact solutions reveals clearly that the nonlocal parameter has the effect of increasing the deflections. In addition, as compared with nonlocal Euler–Bernoulli beam, the shear effect is evident, and an additional scale effect is captured, indicating the importance of applying higher-order beam theories in the analysis of nanostructures.

Analysis of the Chaotic Dynamics of MEMS/NEMS Doubly Clamped Beam Resonators with Two-Sided Electrodes

2018 ◽  
Vol 28 (10) ◽  
pp. 1850122 ◽  
Author(s):  
W. G. Dantas ◽  
A. Gusso
Keyword(s):  
Differential Equation ◽  
Chaotic Dynamics ◽  
Electrostatic Force ◽  
Beam Theory ◽  
Nonlinear Ordinary Differential Equation ◽  
Phase Portraits ◽  
Physical Parameters ◽  
Relevant Parameter ◽  
Practical Applications ◽  
Beam Curvature

We investigate the chaotic dynamics of micro- and nanoelectromechanical (MEMS/NEMS) beam resonators actuated electrostatically by two-sided electrodes, considering devices with realistic physical parameters. We model the resonators using the Euler–Bernoulli beam theory with the addition of viscous damping, midplane stretching and the electrostatic force. For the purpose of numerical simulations, the partial differential equation describing the system is reduced to a one degree of freedom model using the Galerkin method. The resulting nonlinear ordinary differential equation incorporates the main effects of the beam curvature. A comparison with the widely used parallel plate approximation (PPA) evidences the significant effects of the beam curvature. It is also concluded that in the case of resonators with two-sided electrodes special care must be taken when using the PPA. A detailed numerical analysis reveals the region in the relevant parameter space where chaos can be found. Phase portraits, Poincaré sections and bifurcation diagrams are used to characterize the chaotic attractors. The effects of gap asymmetry and damping are also investigated, showing that a stronger chaotic dynamics is favored by small asymmetries and smaller damping. In general, a more complex chaotic dynamics was found, compared to what was initially expected. The results are relevant in view of the potential practical applications in the generation of pseudo-random numbers and chaotic signals for secure communications. The proposed improved model can be easily implemented numerically, helping in the design and simulation of resonators, and the comparison between theoretical and experimental results.

Nonlinear Vibrations of Non-Uniform Beams Including Inertia Effects

2005 ◽  
Author(s):  
Dumitru I. Caruntu ◽  
Ion Stroe
Keyword(s):  
Differential Equation ◽  
Partial Differential Equation ◽  
Boundary Conditions ◽  
Nonlinear Vibrations ◽  
Multiple Scales ◽  
Nonlinear Partial Differential Equation ◽  
Nonlinear Effects ◽  
Order Partial Differential Equation ◽  
Partial Differential ◽  
Inertia Effects

This papers deals with nonlinear vibrations of non-uniform beams with geometrical nonlinearities such as moderately large curvatures, and inertia nonlinearities such as longitudinal and rotary inertia forces. The nonlinear fourth-order partial-differential equation describing the above nonlinear effects is presented. Using the method of multiple scales, each effect is found by reducing the nonlinear partial-differential equation of motion to two simpler linear partial-differential equations, homogeneous and nonhomogeneous. These equations along with given boundary conditions are analytically solved obtaining so-called zero-and first-order approximations of the beam’s nonlinear frequencies. Since the effect of mid-plane stretching is ignored, any boundary conditions could be considered as long as the supports are not fixed a constant distance apart. Analytical expressions showing the influence of these three nonlinearities on beam’s frequencies are presented up to some constant coefficients. These coefficients depend on the geometry of the beam. This paper can be used to study these influences on frequencies of different classes of beams. However, numerical results are presented for uniform beams. These results show that as beam slenderness increases the effect of these nonlinearities decreases. Also, they show that the most important nonlinear effect is due to moderately large curvature for slender beams.

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